A primary DNS suffix can be considered an extension to the computer name separated by a ‘.’ (dot), which is technically known as a period. When an operating system is installed, it does not belong to any domain and therefore it does not have any DNS suffix added to its host name. In home and Small Office/Home Office environments this configuration can be left intact because the numbers of computers in such network setups are limited and they can be located easily by memorizing their IP addresses. The problem arises when the network setup is big and it becomes practically impossible for the users and administrators to memorize all the IP addresses assigned to the computers. In these network environments, it becomes essential for the administrators to install a DNS server, and if computers in such organizations exceed 20 in numbers, they also configure domain controllers for centralized management. Once domain controllers are installed and configured, all the client computers must be manually added to the domain so that they can communicate with the domain controller for better management.

When the client computers are added to the domain, the name of the domain (which is also a DNS suffix) is added to the hostnames of the client computers. An example of a DNS suffix can be ‘myoffice.com’, where ‘myoffice.com’ is the name of the domain. When a client computer with the hostname ‘accounts’ is added to ‘myoffice.com’ domain, the primary DNS suffix is automatically added to the hostname of the client computer to form a complete Fully Qualified Domain Name (FQDN), which would be ‘accounts.myoffice.com’ in this case.

An FQDN is required in these cases because a DNS server only understands DNS queries that it receives from the client computers that have FQDNs.

Benefits of Adding Primary DNS Suffix Manually

As mentioned above, if the computers in any organization exceed 20 in numbers, it becomes essential for the administrators to install a domain controller and add all the client computers to the domain. However if this is not the case, i.e. an organization has less than 20 computers, it is still impractical for users to memorize the IP addresses and therefore a DNS server is still required but without a domain controller. In such an environment, since no client computers are added to the domain because of unavailability of the domain controller, no automatic DNS suffix adding takes place. But since a DNS server only accepts queries from FQDNs, administrators must manually add a primary DNS suffix to the hostnames of the computers to make them FQDNs so that they can communicate with the DNS server.

Adding a Primary DNS Suffix

In order to add a primary DNS suffix on a Windows 7 computer, administrators of the computer must follow the steps given below:

Log on to Windows 7 computer with administrator account.

Click Start, and from the menu right-click Computer.

From the context menu, click Properties.

On the opened window, under Computer name, domain, and workgroup settings section click Change settings.

On the opened System Properties box, make sure that Computer Name tab is selected and click Change button.

On Computer Name/Domain Changes box click More button.

On the displayed DNS Suffix and NetBIOS Computer Name box, specify the appropriate primary DNS suffix in the Primary DNS suffix of this computer field.

Add Primary DNS Suffix

Once done, click OK button and then close all the opened boxes and restart the computer to allow the changes to take effect.

Works as Systems Admin in Siskin Technologies, India. Corporate trainer on Microsoft and Cisco platform. Specialized in Virtualization Technology. LAN Consultant for some local organizations.» View all posts by the author